The invention relates to a method for diagnosing a particle filter used for filtering particles from the exhaust gas of an internal combustion engine, wherein a collecting particle sensor is disposed in the direction of flow of the exhaust gas and wherein a measurement for the loading of the particle sensor is determined from an output signal of the particle sensor.
The invention further relates to a device for diagnosing a particle filter used for filtering particles from the exhaust gas of an internal combustion engine having a collecting particle sensor downstream of the particle sensor in the direction of flow of the exhaust gas and having a control electronics for evaluating an output signal of the particle sensor and for forming a measurement for the loading of the particle sensor from the output signal of the particle sensor.
A method for monitoring an exhaust gas limit value of an internal combustion engine by means of an engine control is described in the patent application DE 102005034247 A1, wherein the engine control has at least one exhaust gas sensor and an error signal is emitted when the exhaust gas limit value is exceeded. The emissions are thereby ascertained for the present driving condition with the aid of an engine model and are compared with the signal of the exhaust gas sensor or a comparison value for the emissions, which is derived from said signal. The particle sensor can be a collecting particle sensor. The method makes the exhaust gas monitoring of deviating operating conditions of the internal combustion engine possible when the driving cycles, for which the exhaust gas limit values are defined, are standardized in relation to each other.
The German patent DE 102006018956 A1 describes a method for determining a mass of particles or a particle mass flow in an exhaust gas tract of an internal combustion engine, wherein at least one resistive particle sensor, whose measured signal change is compared with a predicted signal change ascertained from an engine model, is disposed in the exhaust gas tract of the internal combustion engine. In so doing, provision is made for the measured signal change of the particle sensor and/or the predicted signal change of the particle sensor to be corrected while taking into account the influencing variables on the cross sensitivities of the particle sensor.
The methods make it possible to distinguish between a defective particle filter and one that is still to be considered as intact. The disadvantage thereby is that both methods require a large use of software in the engine control unit, in particular when using a particle untreated emissions model.
It is therefore the task of the invention to provide a device and a method, which make a simplified diagnosis of the particle filter with a reduced application input of software possible.